Juno Delivers Jupiter’s Secrets

"In many ways, it's a new Jupiter," lead investigator says.

Photos from Juno's orbit of Jupiter reveal amazing vistas. Above, the stormy dynamics of the Great Red Spot are visible during a low-altitude pass.

NASA/JPL/SWRI/MSSS/Björn Jónsson

NASA’s ongoing Juno mission, revealing what lies beneath Jupiter’s cloud
tops and in its atmosphere, has upended many long-held theories about the
king of the planets. “In many ways, it’s a new Jupiter,” says Scott Bolton,
Juno’s principal investigator at the Southwest Research Institute in San
Antonio.

Many scientists had thought that by peering underneath Jupiter’s visibly
divided outer layers, they would uncover a uniform, well-mixed planet. But
according to a May study in Geophysical Research Letters, Juno has spied
strong bands of what likely appears to be ammonia, indicating the planet is
churning up material from its depths and implying a more active and
variable world. The probe’s data also show polar regions swarming with
unforeseen storms.

At the same time, Juno is busy sampling Jupiter’s magnetic field, which is
stronger than expected in some places and weaker in others, astronomers
announced in the May issue of Science. And the auroras that light up its
atmosphere arise not just from charged solar particles slamming into the
planet’s atmosphere, as on Earth, but from Jovian moons spewing material
toward the planet.

So far, Juno’s discoveries raise more questions than answers, and
scientists are eager to untangle them. “We’re slowly going to rewrite the
book,” Bolton predicts.